package main

import "fmt"

func factorial(n int) int {
	if n == 0 {
		return 1
	}
	return n * factorial(n-1)
}

func sum(numbers []int) int {
	total := 0
	for _, number := range numbers {
		total += number
	}
	return total
}

func concatenate(str1, str2 string) string {
	return str1 + str2
}

func main() {
	fmt.Println(concatenate("Hello, ", "Go!"))
	fmt.Println(sum([]int{1, 2, 3, 4, 5}))
	fmt.Println(factorial(5))
}
